FRIDAY, Dec. 16 (HealthDay News) -- Draft recommendations meant to increase the number of women in clinical trials for medical devices were released Friday by the U.S. Food and Drug Administration.

Genetics, hormones, body size, diet, social and cultural factors, and types of illness may cause women to respond differently to certain medical products and devices than men, according to the FDA.

But, women are typically underrepresented in clinical trials. For example, a 2009 study of applications for approval of cardiovascular devices found that average female enrollment in important trials that included gender information was only 33.9 percent.

The FDA's draft guidance -- intended for medical device developers and manufacturers -- includes recommendations for designing and conducting medical device clinical trials in a way that may increase the enrollment of women, said Dr. Jeffrey Shuren, director of the FDA's Center for Devices and Radiological Health.

"The FDA recommends that investigators and manufacturers strive to enroll representative proportions of both women and men in their device studies," he said in an FDA news release. "Our draft guidance outlines what we recommend for obtaining and improving the quality and consistency of sex-specific data on devices."

The document covers study and evaluation of sex differences, data analysis, and reporting in clinical studies conducted both before and after market approval. It also deals with statistical analyses of sex differences, how to report sex-specific information in summaries, and sex-specific labeling for approved devices.